Tilted Propeller Layout for Direct VTOL Control Authority
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Solution Overview
Problem
Existing distributed propulsion systems for medium and large VTOL aircraft face challenges in achieving safe flight control due to higher weight and rotational inertia, requiring excessive power margins or complex cyclic and collective controls, which undermine the benefits of distributed propulsion.
Innovation Solution
A distributed propulsion system with propellers symmetrically arranged around the aircraft's center of gravity, each with a tilted plane of rotation, allowing for horizontal force and torque vector cancellation, enabling control of aircraft movement without rolling or pitching, and providing greater control authority with reduced lag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If propellers are mounted in the same plane or parallel planes, then the aircraft structure is simple, but the control authority is insufficient for medium and large VTOL aircraft
Solution Approach 1:
The patent applies asymmetry by tilting the propeller planes at specific angles relative to the horizontal plane. This asymmetric configuration allows the thrust vectors to have both vertical and horizontal components, enabling direct lateral and longitudinal control without requiring the aircraft to roll or pitch first. The tilted propeller planes create control moments that directly counteract the aircraft's rotational inertia, providing sufficient control authority for medium and large VTOL aircraft.
2Reliability
If excessive power margin is added to enhance control authority, then flight control becomes adequate, but the weight and complexity of the system increases
Solution Approach 1:
The patent changes the geometric parameter of the propeller mounting by tilting the propeller planes at specific angles. This parameter change transforms the thrust vector direction, creating horizontal components that provide direct control authority. By optimizing the tilt angle, the system achieves adequate control authority for medium and large aircraft without requiring excessive power margin, thereby avoiding the weight penalty associated with oversized propulsion systems.
3Reliability
If cyclic and collective controls are added to distributed propulsion, then control authority is enhanced, but the complexity and weight of the control system increases
Solution Approach 1:
The patent makes the distributed propulsion system multi-functional by configuring the propeller planes to perform both thrust generation and control functions. The tilted propeller planes can produce vertical thrust for lift, horizontal thrust for lateral/longitudinal motion, and control moments for rolling/pitching/yawing. This universal configuration eliminates the need for separate cyclic and collective control mechanisms, maintaining the simplicity and redundancy benefits of distributed propulsion while achieving adequate control authority.
4Device complexity
If the aircraft must roll or pitch to move laterally or longitudinally, then the control system remains simple, but the response time increases due to rotational inertia
Solution Approach 1:
The patent applies asymmetry by tilting the propeller planes to create direct horizontal thrust components. This allows the aircraft to move laterally and longitudinally without first rolling or pitching, directly overcoming the rotational inertia problem. The tilted configuration enables instantaneous control response by generating the required motion forces directly, eliminating the time delay associated with sequential rolling and translating maneuvers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for efficient lateral, longitudinal, and directional control of the aircraft with reduced control lag and increased authority, eliminating the need for excessive power margins and complex control systems.
Implementation Method 1
a summation of horizontal force vectors created by the tilted plane of rotation of all the propellers is substantially zero when all the propellers are creating a substantially equal thrust magnitude
Implementation Method 2
a summation of horizontal torque vectors created by the rotation direction of all the propellers is substantially zero when all the propellers are creating the substantially equal thrust magnitude
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An aircraft (200; 300; 400; 500) comprises a fuselage (205; 305; 405), one or more support structures (210a-c, 215; 310a-c, 315; 410a-c, 415) connected to the fuselage, the one or more support structures comprising a closed or ring wing (215, 315, 415) and spokes (210a-210c, 310a-310c, 410a-410c), one or more engines or motors disposed within or attached to the one or more support structures or the fuselage, and a distributed propulsion system. The distributed propulsion system comprises two or more propellers (220a-220l, 320a-320l, 420a-420l, 510a-510h) configured in pairs, the propellers symmetrically distributed along the one or more support structures (210a-c, 215; 310a-c, 315; 410a-c, 415) and operably connected to the one or more engines or motors. Each propeller has a rotation direction (225a-225l, 325a-325l, 425a-425l, 512a-512h) within a tilted plane of rotation (235a-235l, 335a-335l, 435a-435l, 514a-514h), and the rotational axes (240a-240l, 340a-340l, 440a-440l, 516a-516h) of the propellers in each pair are substantially coplanar with a vertical axis (245, 345, 350, 445, 518) disposed between the respective pair of propellers, such that a summation of horizontal force vectors (230a-230l; 330a-330l; 430a-430l) created by the tilted plane of rotation of all the propellers is substantially zero when all the propellers are creating a substantially equal thrust magnitude. Movement of the aircraft is controlled by selectively increasing or decreasing a thrust of at least one of the two or more propellers.